Antioxidant and antibacterial activity of silver nanoparticles synthesized by Cestrum nocturnum

ABSTRACT

Background: Silver nanoparticles are toxic to bacteria and have widespread application in differentresearch areas.Objective: The aim of this study was to synthesize silver nanoparticles using an aqueous leaf extract ofCestrum nocturnum and to test its antioxidant and antibacterial activities.Materials and methods: The silver nanoparticles were synthesized by addition of 20 ml extract (8% w/v)with 180 ml silver nitrate solution (1 mM). The synthesis of silver nanoparticles was confirmed byUVeVis spectrophotometer. The silver nanoparticles were characterized by X-ray diffractometer,Transmission Electron Microscope, Scanning Electron Microscope and Fourier Transform Infra-Redspectroscopy. The antioxidant property of silver nanoparticles was analyzed by the 2, 2-diphenyl-1-picrylhydrazyl, hydrogen peroxide, hydroxyl radical and superoxide radical scavenging methods. Thebacteriostatic and bactericidal activity of silver nanoparticles against Escherichia coli, Enterococcus faecalis, and Salmonella typhi was determined using bacterial growth inhibition method. The antibacterialsensitivity and Minimum Inhibitory Concentration (MIC) of silver nanoparticles was determined againstthe bacteria.Results: The results confirmed that the silver nanoparticles synthesized by C. nocturnum extract werecrystalline in nature, average particle size was 20 nm and were mostly spherical in shape. The antioxidant methods confirmed that the silver nanoparticles have more antioxidant activity as compared tovitamin C. The silver nanoparticles have strong antibacterial (maximum Vibrio cholerae and minimumE. faecalis) activity. The MIC value of silver nanoparticles was 16 mg/ml (Citrobacter), 4 mg/ml (E. faecalis),16 mg/ml (S. typhi), 8 mg/ml (E. coli), 8 mg/ml (Proteus vulgaris), and 16 mg/ml (V. cholerae).Conclusion: Green synthesized silver nanoparticles have strong antioxidant and antibacterial activity dueto the presence of bioactive molecules on the surface of silver nanoparticles.© 2018 Transdisciplinary University, Bangalore and World Ayurveda Foundation. Publishing Services byElsevier B.V. This is an open access article under the CC BY-NC-ND license (http//creativecommons.org/licenses/by-nc-nd/4.0/).